The present invention relates generally to the use of strength identification in the design and implementation of control systems for exercise equipment, and more particularly to a method and apparatus for strength identification and control of an exercise machine based upon the velocity dependence of the strength of the user.
Improvements or atrophy in muscular capacity are related to the type of activities performed. For example, an astronaut living in a gravity free environment requires very little strength to perform his daily tasks; thus over time, the astronauts' body will lose its muscular definition. On the other hand, a bodybuilder will increase his strength over time due to the repetitive loading of the various muscle groups. This idea has been formalized with the so called "Principle of Specificity." This principle states that an important factor in establishing a training routine is to try to develop exercises that will train the body in a highly specific manner, thereby improving its response to the precise demands that will be placed upon it in competition or in everyday life. By training the body in a highly specific manner it is thought the proper neural and physiological adaptations take place in the body. For example, endurance training increases the number of mitochondria in the muscle cell making it more able to metabolize fats.
Typically exercise machines are configured to take advantage of the Principle of Specificity in two ways. First, by isolating a particular muscle, or group of muscles, and then by providing the particular resistance desired by the user. Usually, the resistance provided by the exercise machine can be categorized into one of three groups: "isotonic" (constant torque), "isokinetic" (constant velocity), or "isometric" (constant position). Furthermore, in some of the state-of-the-art exercise machines, a variable radius cam is used in conjunction with a weight stack so that a configuration dependent resistance is achieved. This position dependent resistance is important because of the varying geometry of the musculoskeletal leverage system.
Prior art exercise machines may incorporate some type of program that controls torque or velocity which may be selected by the user. It is believed, however, that no prior art machine identifies the strength characteristic of the user and adapts the exercise program to the user based on the strength data gathered. For example, U.S. Pat. No. 2,777,439 discloses a method of providing a resistance which varies with position. U.S. Pat. No. 2,921,791 discloses a device which provides a constant resistive torque. U.S. Pat. Nos. 3,212,776; 3,465,592 and 3,784,194 disclose machines which automatically adjust resistance to maintain a constant speed of exercise motion. Likewise, U.S. Pat. Nos. 4,184,678; 3,848,467; 3,869,121; 4,082,267 and 4,261,562 disclose various methods of producing and electrically controlling a resistive torque to produce a preselected program of a plurality of constant velocity motions. U.S. Pat. No. 3,589,193 discloses several methods of providing predetermined types of resistance torques in an ergometer.
None of the prior art exercise devices discussed above provide a method of testing user strength and adapting the resistance accordingly to provide a specified type of workout. An object of the present invention is to provide a method of testing the strength characteristic of a user of an exercise machine and controlling the resistance of the machine based on the strength data gathered.
Another object of the present invention is to provide a method of optimizing the power output of the user.
Another object of the present invention is to provide a controller which has the desirable property of being passive (i.e. safe to operate) and can regulate the velocity of the workout to conform to a desired position dependent function which may be specified by a performance index.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out in the claims.